

MINE SUPERINTENDENTS, 
MINING ENGINEERS, 

MINE FOREMEN, 

MINE OWNERS, 


It is necessary that you be informed in the progress in the sci¬ 
ences related to mining, and in the improvements in mining ma¬ 
chinery and mining methods. To do this you must read the Trans¬ 
actions of all the Mining and Scientific Societies of the United States 
and Europe, to become a member of which will cost over $200 a year 
and you must expend more time thau you can afford in reading 
these proceedings. 


T 

Publishe 

MIf 

scriptior 

author. 

By rev 
perform 
fill a pla 
with 


E 

L 


LIBRARY OF CONGRESS, 


dlpp*_iapijripfjt In,.._ 

Shelf .XHL6Q 

yi tl k 

UNITED STATES OF AMERICA. 


ning 

r de- 
; and 

le we , 
, and 
ished 


Condensed as much as the importance of the subject will permit. 

Those who subscribe now, can be supplied with bapk numbers 
from the beginning of volume VIII, issue of August, 1887. 

The price of subscription is $2.00 per year. 

SAMPLE COPIES SENT FREE ON APPLICATION. 

Yours truly, 

THE COLLIERY ENGINEER Co., 

Coai. Exchange, Scranton, Pa. 

Publishers, Importers, and Dealers in books relating to Coal and 
Metal Mining, Drafting Instruments and Supplies, and Proprietors 
of The Correspondence School of Mines, and The Correspondence 
School of Mechanics. 

SEND FOR CATALOGUE. 





















MINING PRIMERS. 


G E OLOG Y. 



BY 


M. C. IHLSENG, C. E., E. M., 

PROFESSOR OF 


Ph. D. 


ENGINEERING, STATE SCHOOL OF MINES, GOLDEN, COL. 


(REPRINTED FROM EASY LESSON DEPARTMENT OF THE COL¬ 
LIERY ENGINEER.) 








Entered according to the Act of Congress, in the gear 1898, kg The 
Colliery Engineer Co., in the office of Librarian of Congress at 
Washington. 


U 




TABLE OF CONTENTS. 


Chapter I. —Coal and its Formation 

QUESTION. PAGE. 

1. The Composition and appearance of the dif¬ 
ferent varieties of coal. 1 

8. How coal was formed. 11 

11. Coal pipes or sigillaria. 12 

14. Explanation of fossils. 13 

17. Fossils of the Carboniferous period. 15 

18. The history of the earth’s formation. 15 

Chapter II.— Stratified Rocks—Theik Formation 
and Changes. 

QUESTION. PAGE. 

20. How strata were formed. 19 

29. The thickness of the stratified rock. 20 

32. Formation of the Rocky Mountains. 22 

35. Explanation of “folds” or “rolls”. 22 

38. Faults. 24 

40. Rock faults. 24 

*47. Cleat.*. 26 















Chapter III. —The Amount of Coal is the United 
States—The Formation of Iron Ore Beds. 

QUESTION. " PAGE 

56. How long before the coal will be exhausted. 29 

62. The thickness of coal seams in different districts 30 
64. The time required to form coal seams. 31 

66. What ore is. 31 

67. What mineral is. 31 

70. The different ores of iron. 32 

72. How iron ore beds were formed. 32 

81. The proportion of iron in different ores. 33 

82. The principal iron producing districts of the 

United States. 34 

89. The formation of petroleum. 35 

Chapter IV. —Natural Gas and Petroleum. 

QUESTION. PAGE. 

92. The formation of Natural Gas . 36 

94. The territory and formations in which Nat¬ 
ural Gas is found. 36 

100. Spouting wells and dry wells. 37 

102. How gas and oil are accumulated underground 38 

103. Where to bore for oil or gas. 39 

107. The production of petroleum in the United 

States and Russia. 40 

109. The relation between the origin of coal and oil 41 

110. The composition of Natural Gas. 41 

















Chapter V.—The Distillation of Petroleum—The 
Comparative Value of Natural Gas, Petroleum, and 
Coal as Fuels. 


QUESTION. PA«E, 

112. The Uses of Petroleum. 4 

113. The Distillation of Petroleum . 43 

115. The Amount of Different Substances Obtained 

from Pennsylvania Petroleum. 44 

119. The Amount of Heat Produced from Fuels. 45 

124. Comparison of Values of Petroleum and Coal 

as Fuels. 46 

127. Comparative Value of Natural Gas and Petro¬ 

leum as Fuels. 47 

128. Asphalt. 47 

Chapter VI.— Plutonic and Volcanic Rocks. 

QUESTION. PAGE. 

131. Where Minerals Occur.. 49 

133. Massive Rocks. 49 

135. Where Plutonic Rocks Occur. 49 

136. The Composition of Granites. 50 

137. Where Volcanic Rocks Occur. 50 

138. The Composition of Porphyries. 50 

140. The Primary Rocks of the Earth. 52 

144. The Theory of the Formation of Granites. 55 

' Chapter VII.— The Occurrence of Ores —How De- 

POSITED. 

QUESTION. PAGE. 

145. Definition of Veins and Beds. 58 

147. How Ores were Deposited. 58 

149. Where Metalliferous Veins are Found. 60 




















Chapter VIII— The Formations or Veins and Values 
of Different Ores. 


QUESTION. PAGE. 

157. The Appearance of Veins and Ore Beds. 64 

159. Forms and Combinations in which* Gold, 

Silver, and other Metals are Found. 65 

160. The Values of Different Ores... 68 

161. The Effect of Different Impurities on the 

Values of Ores. 70 

162. Changes in the Mineral Character of a Vein 

at Different Depths. 71 

163. The Formation of Ore-Belts. 71 

165. Method of Tracing Intersecting Veins. 73 









CHAPTER I. 


1. What is coal ? 

Any mineral substance containing sufficient carbon 
to supply its own fuel and be capable of burning. The 
line between the various fuels is not easily drawn. 
There are all grades of coal with vegetable matter at 
one end of the series and graphite at the other, includ¬ 
ing peat, lignite, soft bituminous hard coal, and 
graphite. 

2. What is the difference between these varieties ? 

If you read the lectures on chemistry you will 

notice that every piece of organic matter, leaf, wood, 
flesh, etc., has carbon, hydrogen, and oxygen in it in 
different proportions. According as these elements 
differ in quantity, so they produce wood, grass, 
or flesh. For example, wood is made of minute 
particles of carbon, of hydrogen, and oxygen. 
The same is true of the coals, of which here 
is a table to show their composition. For simplicity 
we put C. for carbon, H. for hydrogen, and 0. for 
oxygen. 



10 


MINING PKIMEK8. 



C. 

H. 

O. 

Vegetable matter has about. 

•49 

•06 

•45 

Peat has about. 

•56 

•06 

•37 

Lignite has about. 

•70 

•06 

•24 

Block coal has about. 

•75 

•05 

•15 

Soft coal has about. 

•88 

•06 

•06 

Hard coal has about. 

•95 

.03 

02 

Graphite has about. 

100 

00 

•oo 


The progressive order of the series is still more notice¬ 
able when < ne reduces the cases to percentages in com¬ 
bination with 100 parts of Carbon, though the table 
does show that the Carbon increases in amount. 



C. 

H. 

0 . 

Vegetable matter. 

100 

123 

91*1 

Wood. 

100 

12-2 

83-1 

Teat. 

100 

10*8 

66-1 

Lignite. 

100 

85 

343 

steam coal. 

100 

68 

6-8 

Anthracite... 

100 

31 

2-1 

Grajhite. 

100 

0 

0 


3. Why are they so different? 

Because these coals were made at different times. 

4. How do you know that? 

Because they never occur near each other and they 
look so very much unlike one another. 

5. Please explain what you mean ? 

Graphite is a pure carbon just like the diamond, and 
has a fine grain, is smooth and shiny, like steel. It 
leaves no ash after burning. 











































GEOLOGY. 


11 


Anthracite is a hard stone coal, with a very little ash, 
and burns without smoke. 

The bituminous coal is soft, blazes up with a flame, 
swells, and finally bakes into a spongy mass called 
coke. There are many varieties called cannel, coking, 
cherry,splint, or block. 

Lignite is a poorer quality of coal that leaves behind 
a great deal of ash, and is brown in color showing 
often the fibres of wood in it. 

Peat is a matted mass of rotting vegetation. 

6. Where are these varieties found ? 

Graphite is not very common, and occurs in thin 
seams. 

Anthracite is found in Pennsylvania and Colorado, 
where the rocks have been disturbed, or broken up. 

Bituminous coals are found all over the world, as a 
wise provision of nature for the comforts of man. 

Lignite, or brown coal, is mined in the Western States. 

7. Is there any theory to account for them? 

Yes, it is one which the geologists have formed from 
their observations and knowledge of the behavior of 
the forces of nature. 

8. What is it? 

Have you ever noticed the marshes and bogs, how they 
are the rotting masses of vegetable and organic matter ? 
If they are not disturbed fora number of years the marsh 
becomes deep and large. In the swamps of Louisiana. 
Arkansas, an l Mississippi are very deep bogs, in which 
also grow large trees, close together. When these die, 
fall, and rot, a thick bottom of carbonaceous matter is 
deposited. When the water is absorbed, or if the bog 
becomes dry, a peat is formed, which can be cut and 
burned. Throughout Ireland, and in many countries 
are thick, rich bogs of the peat, some quite compact 
and dry. In any swamp we can find a depth of this 
black, half decayed wood. Then the land sinks, 
or the sea rises, and covers the peat with sand and mud, 



12 


MINING PRIMERS. 


just as we have seen off the shores of Guernsey and off 
Devonshire. The peat becomes buried, pressed to¬ 
gether by the materials above it, and in time it assumes 
the shape like lignite, light, and having one-tenth of its 
weight in water. A further change, as time wears on, 
produces the forms of bituminous coal. With greater 
time, pressure and heat anthacite is formed. If it is 
still longer heated graphite or plumbago is formed. 

9. How long has this change been going on ? 

Geologists cannot tell but it must have taken ages. 

The amount of coal that supplies U. S. inhabitants 
alone, is 150,000,000 tons every year, and men tell us that 
there is sufficient under ground to keep up the 
supply for an indefinite peroid. The time required to 
make all this coal out of wood is very great. (See Q. 59). 

10. What evidences have you of this theory? 

First, the microscope shows coal is full of leaves, 
fibres, and bark of trees. Then near Richmond w r e see 
a bituminous bed of coal that has been changed in 
places to anthracite where a 
thin sheet of lava has touched it. 
And we can make coal by put¬ 
ting saw-dust under heat and 
great pressure. 

11. Have those “coal pipes” 
that occur in the roof any con¬ 
nection with coal formation ? 

Those are called “ sigillaria.” 
They are tree trunks that were 
standing when the mud formed 
around them. You will notice 
them in the roof as saucer¬ 
shaped. As they are the base of 
trees near the roots and taper 
thinner upward they are liable 
to drop down, so always stand from under and prop 
them at once. In looking for coal (prospecting that is 



Fig. 1. 












GEOLOGY. 


13 


called) the finding of sigillaria is a sign of being above 
the coal. On the preceding page is a picture of them, 
Fig. 1. The scars are where leaves once grew. 

12. There must have been immense forests to furnish 
so much timber and vegetation ? 

There were. If you have seen the large and dense 
swamps of the Southern States that hid so many 
negroes during the Kebellion ; or the illustrations of 
Brazilian and African woods you will readily see that 
the illustration, Fig. 2, (on next page) is simple in 
comparison. It shows what the geologists believe to 
have been the forests of the coal period. 

13. Now there are three things troubling me. First, 
how does this theory come to have been formed ? 
Second, what do you mean by coal period ? Third, 
I do not understand what you say about the mud form¬ 
ing around the “ pipes ? ” 

That is a long story, but I will answer your second 
first. Have you noticed that coal contains different 
kinds of leaves, roots, etc.? Well they indicate to us 
that these plants existed at the time that the trees were 
growing. We call that the coal period. 

14. How was the theory formed ? 

It was developed from observation of what is now 
going on. A leaf falls into the stream and becomes im¬ 
bedded in its mud. A twig falls on the ground and is 
covered by sand. An animal dies on the plains, its 
bones are bleached. A rain washes them into a creek, 
and they are covered with sand. If in time these are 
buried under the soil, they give form to the sand that 
packs around them and a “ fossil ” is produced. That 
explains the coal pipes that had been growing in a 
marsh and stood many hundreds of years after the 
marsh had been covered by a stream that had deposited 
mud around the tree. We know that old forest trees 
live perhaps a thousand years. 




MINING PRIMERS. 

















































































































































































































































































































































































































































































GEOLOGY. 


15 


15. l)d animals live daring that time? 

Yes; there were beetles, spiders, and other insects. 
There were some air-breathing, back boned animals, 
like our water dogs. There were no birds, no serpents, 
no fruits, no flowers. Fishes were plenty. 

Id. Are there any fishes in the coal ? 

Occasionally they are found to give life to the dead 
wa^te, but they are generally found in the slates and 
(•lays above and below the coal. 

17. Is that the reason that certain rocks are called 
carboniferous, or of coal period ? 

We always know how and where to look for coal. 
The finding of fossils is our guide. For example if I 
find in a certain rock, remains of 
the five-fingered leaves, like that 
shown in Fig. 3, I know I am 
too high to look for coal and must 
go down. And if a rock is found 
with the lower forms of life, like 
those of Fig. 4, I am too low 
down in the rocks. Carbon¬ 
iferous rocks will have shells like 
those shown in Fig. 5. 

18. What do you mean by say¬ 
ing “ too low down ? ” 

The question involves the 
whole history of the earth’s forma- Fig. 3. 

tion. All the rocks are in layers 

which occur in the same order wherever vou go. Some 
layers may be missing or very thin, and in other places 
they will be thick. The order is, however, the same. 
Granite is always at the bottom and is called the base¬ 
ment of the earth. Then come a variety of sandstones, 
slates, clays, and limestones, of different colors and 
natures. 

Some of the bottom layers of these have fossils like 
those in Fig. 4, and are called Silurian. Above them 




16 


MINING PRIMERS. 



Fig. 4. 



















GEOLOGY. 


17 


will come layers having fishes, called Devonian ; corals 
were also numerous. On top of these, never below 
them, came again series of slates, limestone, etc., (car¬ 
boniferous) that are full of plants, fossils, or shells like 



Fig. 5. 

Fig. 5. Above them came layers and layers of these 
same rocks carrying corals in sixes , not in fours as were 







18 


MINING PRIMERS. 


those of the Devonian , and equally-split -tailed fishes, and 
above all reptiles like those in Fig. 3£. 

These layers included the Jurassic , Triassic, and Cre¬ 
taceous periods. During the last-named there also exist¬ 
ed great forests to produce the 
coals of the Western States. 

After the Cretaceous we had birds 
appearing in the Tertiary rocks, 
and finally mammals. 

So you see there is perfectly uni¬ 
form order which can always be 
identified by the kind of fossils 
the rocks contain. The more 
nearly the animal or plant resem¬ 
bles those of our . ay the higher 
up the rock is. 

19. Are these rocks always of 
same thickness? 

No, for they were made under 
different conditions of the earth 
and may be one foot thick in 
Pennsylvania and 50 feet thick in Germany. The car¬ 
boniferous is very rare in Colorado. Again the rocks 
were formed like the peat as mud deposits of a creek, 
or lake, or ocean, so they will be thin near the banks 
and thick in the deep water. 



Fig. 6. 







CHAPTER II. 


20. What are strata ? 

That is a term used in speaking of several layera. 
One is called a stratum. Two or more are strata. 

21. Is that where “stratified rocks” comes from? 
As the rocks like limestone and slate are flat layers 

we call them stratified. 

22. Is granite stratified. 

No, it is a massive rock. 

23. Then it was not produced by seas or creeks ? 

No, granite is the foundation rock of the earth and 
when as the Bible says, this earth assumed form, it be¬ 
gan to be worn away by frost and water. The coarse 
heavy material was washed to the bottom of the hill 
and there it was left while the sand and mud were car¬ 
ried further on. Soon the current became too slow 
and the sand accumulated while the lime grains were 



carried along with the clay mud. Afterwards the lime 
settled out and the mud formed a bottom way out in 
deep water. If the operation continued long we had 







20 


MINING PRIMERS. 


sandstone, limestone, and clay. Then if there was a 
drought, or the sea dried up, all the plants and animals 
went with the soil and they were buried. 

Then a flood and a new sea formed later and began 
the same process of eating away the granite to form, 
perhaps, the Devonian, and so on. It is the same as is 
going on to-day. (See question 8, Surface Appliances.) 

24. What are the slates made of? 

They are the same as clay but they have been 
hardened more than the clays. 

25. Then, the coal must have been formed in v£ry 
quiet water, a pool or ocean? 

Yes, how did you come to see that? 

26. Because usually our coal seams have clay or s’ate 
roof and floor. Then in years to come will we be fossils 
for future geologists ? 

Yes, drowned sailors lying in their wet graves are 
being slowly buried with whales and corals in the ever- 
settling sediment. The whole history of the earth has 
been one ceaseless action of rain and sea that carries 
everything to the ocean, the bottom of which is and 
has been a cemetery in which lie the dead from the 
three kingdoms of nature—the earth, air, and water. 

27. How long has this been going on? 

We can not tell, certainly a long time. 

28. Is the whole crust of the earth stratified above 
the granite? 

Yes, and all are called sometimes sedimentary rock as 
well as stratified. The first name refers to the mode of 
formation, the second to the manner of its occurrence. 

29. How thick is the stratified series? 

The crust of the earth is 50 miles thick and the strat¬ 
ified rock constitutes from a mile to ten miles of it. 

30 Has any one ever seen the bottom granite? 

Oh yes. Sometimes the stratified rocks on the granite 
are not deep «nd a bore hole has been drilled down 
into it Sometimes very deep holes, nearly a mile, have 




QV f° v r ^ vv 


v V -* 
v^ v/ ✓ 

✓ V' 


* V 

*> ^ V’ V 

»> V */ V* — Vt*+* 




V 




V, 


vm^ r 
'^' •>. 1/ 




C 1/ 


q3^ N 

, 0.-* 4 

































22 


MINING PRIMERS. 


failed to reach even the carboniferous.. In other places 
there are no stratified rocks to hide the granite. 

31. Why is that ? 

Such places may have been the original hills of the 
earth against which all the seas have beaten. In 
Canada and the Adirondack Mountains are remains of 
these primitive hills. 

32. May they not have been thrown up through all 
these strata? 

Not there; but the Rocky Mountain range was 
formed in that way. 

33. Did the mountains break right through all the 
strata ? 

Yes, for all along them North and South you will 
see the rocks standing up on end like in Figure 8. At 
places the wall stands 300 feet high. It is this which 
makes the Garden of the Gods so famous There, the 
rocks stand hundreds of feet high in walls and towers. 

34. Is the Silurian next to the granite ? 

No, not here. Elsewhere it is next. The carbonif¬ 
erous was broken off below, but was not pushed up to 
the surface. In this figure you will see that the granite 
has shoved up through the strata and broken them off. 
The further away you go from the mountains, as away 
out to the right of the figure, the rocks are less disturbed 
and you will notice that they become flat. So they 
extend under the plains, under Missouri and Ohio for 
nearly 2,000 miles to the Alleghany Mountains where 
they again stand up. Some of the Anthracite coal seams 
are steep instead of flat. The coal marked to the right 
is cretaceous. We know, too, that the Rocky Moun¬ 
tains were tipped up because on the other side the 
rocks are broken off dipping towards the West. And 
also a few patches were carried up on the tops. Fig. 10. 

35. I should think the strata would be broken up by 
this uplifting. Are they ? 

Yes they are. You must remember that the quiet 




GEOLOGY. 


23 


depositing of mud as I explained was going on whiie 
the earth was cooling. As it cooled, the strata shrunk 
and in doing so became squeezed. The layers were 
bent and distorted just like a number of sheets of paper 
would behave under a side pressure that squeezed 
them. 

36. What are these called ? 

They are called “ folds ” or “ rolls.” You must have 



B 

Fig. 9. 


noticed them in the mine. Fig. 9 is from an actual 
case. Fig 10 is also another case from on top of the 
Rocky Mountains a mile above sea level. The dotted 
lines show where it is believed the strata united A 
B and C are valleys and creeks. At Tamaqua, Penn., 
the Mammoth coal bed, as it is called, is bent like the 
letter U coming out on Sharp Mountain at one end and 
Locust Mountain at the other. 



Fig. 10. 

37. With these bends and rolls I should think the 
strata might be broken ? 













24 


MINING TRIMERS. 


They often are broken fine or else they crack just 
as is shown in Fig. 11. 



Ftg. 11. 

38. What are the cracks called? 

“ Faults ” is the proper name for these breaks but 
miners call them “ thrusts,” or “ throws.” 

39. Why are they so called? 

Geologists call them faults. They are breaks in the 
strata, across them. For example, if the rocks in Fig. 
9 were to break, the fault would be along A B. But it 
seems that besides cracking, the strata fell and are mis¬ 
placed as in Fig. 11, where A and B are coal seams. 
The right hand side slipped on the fault line. As these 
faults generally cause a settling of one side or the other, 
the miners have called them “ throws ” as if one side 
was thrown up or thrown down. 

40. What do the miners mean by “ rock faults ” or 
slate faults ? ” 

These are not, truly, faults but they are names which 
the miner uses for portions of the coal beds which are 
thinner and have slate or sandstone where some of the 
coal ought to be, as S in Fig. 12. They call them 
“ horses ” in ore mining. 
























GEOLOGY. 


25 


41. Faults, then, are places where the rocks have been 
broken and afterwards displaced? Is there ever any¬ 
thing in those cracks? 

Oh, yes. In regions where volcanoes exist and where 
earthquakes are common, the faults are often filled with 


ROOF 



Fig. 12. 


lava from the volcanoes or with .silver and lead ores. 
In the coal regions, however, they rarely have anything 
but dirt and fine rock. 

42. Are faults common? 

I know of only three in the Pennsylvania Bitumin¬ 
ous region. There are several in tlie Anthracite districts. 
They are quite numerous in the Western States but not 
common in Virginia, Illinois, or Missouri. 



Fig. 13. 

43. How far do the rocks slip ? 

They may be as much as 20,000 ft. The average may 












26 


MINING PRIMERS. 


be said to be 20 feet. But in Utah there is a throw of 
10,000 feet. And in Pennsylvania and Virginia the 
sinking is over 30,000 feet. 

44. Are they ever near together ? 

Look at Fig. 13 which is a good example from England. 

45. How do you know but they may be separate beds 
which never were connected ? 

Do not you recall what I s-aid about fossils ? 

Well, each different rock will have some distinct 
variety of shell fish or leaf by which we can recognize it. 
When the rocks are similar they have the same kinds 
of fossils. 

46. Then by the fossils you know where to look for 
the rest of the coal seam ? 

Yes, if I am mining one of those coal seams and 
strike a fault, I go over to the other side, examine the 
rock and then by its fossils I can tell whether the 
thrust has been up, or down. And I go accordingly. 
Don’t you see how important fossils are ? 

47. Have these faults anything to do with the cleat 
of coal? 

Not at all. By the name of “ cleat ” we mean the 
joints in the coal All rocks have joints and split along 
them giving smooth surfaces. Slate cleaves into thin 
slabs, and building stones have also that tendency. But 
besides breaking into slabs, many stones break cross¬ 
wise into blocks more or less like a cube. The joints 
along which the stones naturally break are called cleav¬ 
age joints or “cleats.” These joints are natural to 
every material. Even volcanic rocks, as we shall soon 
see, have cleavage planes. 

48. Are the cleats the same distance apart in all coals ? 

No. The soft coals have the cleats nearer together 

than the hard coals. But for a particular coal they 
are the same distance apart. Sometimes they are in 
such directions as to give a cubical shape to the coal. 
At other times, the cleats are at an angle. 



GEOLOGY. 


27 


49. What is the cause of cleats? 

It is the natural condition of the coal just as the 
“ mundic,” “ iron,” or “pyrites” in the coal always 
occur in the form of cubes. 

50. Are cleats of any help to the miner? 

Yes, indeed. The coal breaks off easily at these joints 
and so the hewer will cut under as far as a cleat and 
then let the coal fall. To make this possible, it often 
happens that direction of the cleat fixes the direction 
of the working faces. So the rooms are turned off from- 
the gangways as that their faces shall be with cleat. 
Mines working by the “pillar and stall ” method can 
take advantage of the cleat in this way. Those work¬ 
ing Longwall can not always. In Anthracite, the cleat 
is not an important enough matter to determine the 
direction of the working faces. The coal seams are 
generally too steep there. 

51. How does the coal look on the cleat? 

Smooth and shiny. 

52. Can you explain the methods of mining as you 
mentioned them ? 

I leave that to another time. 

53. Is the coal often crushed badly by these folds, 
bends, and faults ? 

Oh yes. In the hollows of the sharp bends there is 
a great deal of finely broken coal. The quality of the 
coal is very much injured and the loss by waste is often 
very high from this cause. 

54. May it be that the “ dirt faults ” and “ rock faults ” 
are caused by grinding of the strata on each other ? 

Yes, the name of dirt fault is often applied to places 
where the coal has been badly broken up. Sometimes, 
though, the term like that of rock fault or slate fault 
is used to express the idea that the coal has thinned 
out and is replaced by dirt, rock, or slate. 

55. What are “ partings ” ? 

They are seams of clay or slate found in the coal beds 





28 


MINING PRIMERS. 


that divide the coal into several layers. Rarely is a 
coal bed without them. They occupy on an average 
one-seventh of the entire thickness of the bed. These 
partings are mud deposits that show the bottoms of the 
ancient marshes had been raised or that the currents 
flowing through them had changed in direction or 
speed. 



CHAPTER III. 


56. What is the amount of coal yet remaining inKthe 
U. S.? 

That is hard to say. But the Census Bureau esti¬ 
mates 250,000 square miles of coal beds of all varieties 
and thicknesses. Assuming 5 feet as the average thick¬ 
ness of the coal, and an average of only 1000 tons of coal 
that can be recovered from every acre of coal bed of 
one foot thickness, we have: 

250,000 X 640 X 5 X 1000 = 800,000,000,000 tons as 
the total amount of coal. 

57. How long will that last ? 

Last year there were sold and used 128,000,000 long 
tons. At that rate there is supply for 6250 years. But 
population is increasing, and the demnad increases like¬ 
wise. From the past experience, it has been found 
that the consumption doubles every 16 years. On this 
basis, in 190 years all the coal will have been burned 
up unless other sources of power and of heat are mean¬ 
while discovered or more economy shown in the burn¬ 
ing of fuel. 

58. Am I to understand that all coals are made of 
the same vegetable decay ? 

We believe so, that club mosses, ferns, and trees like 
our ground pine furnished the most of the mineral coal 
of the Carboniferous age. 

59. How about the can n el coal ? 

That is a compact smooth breaking coal which will 
light with a match just as a candle would. It is formed 
of the finer grained marsh weeds. 


30 


MIXING PRIMERS. 


60. I can not understand how so much coal could 
he formed from one marsh. For the peat and wood 
must have lost much of its oxygen and of its weight in 
being compressed to coal ? 

Yes, so it has ; wood actually loses three-fifths of its 
weight in being altered to Bituminous coal, and three- 
fourths of it is lost in being changed to Anthracite. 
Besides this, the decayed matter is compressed and loses 
in bulk. So that, altogether, it took about 5 feet of veg¬ 
etable marsh to make one foot of Bituminous coal and 
8 feet to produce one foot of Anthracite. 

61. How thick is the coal? 

Coal occurs in marshes very thin at the edges and 
thick in the middle. In some places a single bed is as 
thick as 40 feet (one in Colorado is 90 feet thick) but a 
pure seam is seldom over eight feet. Anything over 
that is a compound seam, in which the streaks are sep¬ 
arated by thin partings. 

62. How many coal seams are there in a district? 

In Pottsville, Pennsylvania, there are 113 feet of coal 
seams; and in the U. S. the largest number of seams, 
one above the other is 42. In Wales there are 100, of 
which 70 are worked. In Nova Scotia there are 81 
workable seams at various depths from the surface. 

63. Did you say that these different seams were 
caused by the ocean overflowing the land several times ? 

Yes. The forests and swamps were covered by sedi¬ 
ments and became hidden from view. The marshes 
sank during the disturbances that followed. Then the 
ocean flowed over it and brought more mud. The peat 
bog compressed and coal began to form there under the 
clays. After a rest, during which more mud and sand 
was deposited, more disturbances occurred. Some 
ground went up, some fell. Forests began to grow and 
more ferns flourished to form marshes.- After these 
had decayed, another sinking is supposed to have taken 
place, and another mass of peat was buried to after- 




GEOLOGY 


31 


wards form coal. This must have been repeated as 
many times as there are seams of coal. Sometimes salt 
water covered the marsh, sometimes it was fresh water. 

64. How long did all this take ? 

I have seen estimates making it' over a million years. 

65. How is that measured ? 

An ordinary forest will make about 2000 pounds of 
organic matter per acre each year. This is 200,000 
pounds in a century. One hundred tons compressed 
to be as heavy as coal will make 2420 cubic feet. If 
these are spread over an acre of 43560 square feet sur¬ 
face, they will form a layer only two thirds of an inch 
thick. But in the formation of coal four-fifths of the 
material escapes as gas, oil, or water, and only one-fifth 
remains in it, therefore it must take 500 years, instead 
of 100, to make a layer of coal two-thirds of an inch 
thick. For a coal seam of the standard size, four feet, 
it must therefore have required 72 times 500 years to 
make it, or 36,000 years. But some coal regions have 
over 100 feet of coal. To form the coal alone would 
--therefore require aboutfKX),000 years. Think of it! And 
we are using it up so very fast that we have perhaps 
only enough for the sixth generation beyond our own. 

66 What is meant by an ore? 

An ore is an accumulation of mineral in such quan¬ 
tity and of such a quality as to pay for mining. 

67. Wbat is a mineral? . 

A mineral is the compound of a metal in chemical 
union with a non-metallic substance, as sulphur, car¬ 
bonic acid (the choke-damp of min.es), etc. 

68. Will vou give some < xamples ? 

Iron and sulphur make a mineral called pyrites; 
lead and sulphur give a mineral known as galena ; iron 
yith oxygen makes a very common iron riiineral, and 
silver with arsenic and sulphur is often seen. And 
When a big bed of any of these minerals is found it. is 
mined for the ore of iron, of lead, or of silver, 






32 


MINING PRIMERS. 


69. Is pyrites a common ore of iron ? 

No. Pyrites is the commonest occurrence of iron in 
the earth, but it is mined not for iron manufacture but 
for the sulphur in it. Hence it is not an iron ore. It 
does not pay to roast off the sulphur and make iron of 
if when there is so much of a better mineral to be had. 

70. What is the ore of iron ? 

The several ores are all varieties of the compound of 
iron with oxygen. They are called hematite, limonite, 
or magnetite. 

71. Where are they found? 

In the sedimentary rocks between the strata, like 
coal; and often very thick. 

72. How were these beds formed, like coal ? 

Not exactly like coal but yet very similar, in that 
water and vegetable and organic matter have had a 
great deal to do with the deposit. 

73. What is the process? 

We judge only by what is going on now. Taste the 
waters of a bog as they ooze from the soil. The taste 
is inky. The water is colorless. A chemist would tell 
you that there is iron in it. Where did it come from ? 
I will tell you. Where are the iron bogs seen ? Any¬ 
where and everywhere. Do you remember my saying 
that pyrites was a very common mineral? It is every¬ 
where,—in coal, in clay, in sandstone and in nearly all 
the rocks. Water is a great and powerful solvent. It 
can leach out of any rock some of the matter it con¬ 
tains. Well, it will dissolve, or wash away pyrites 
which naturally accumulate in the marshes. 

74. But we do not find pyrites there ? 

No you do not for the moment, wet pyrites comes out 
into the air it rusts (that is, it takes oxygen from the air) 
and you will notice a scum floating on top of the water. 
That is iron rust. By and by the rust sinks to the 
bottom and as more of it is washed in here, a layer of 
iron mineral is formed. 



GEOLOGY. 


33 


75. Why, it is just like coal formation! 

Yes, this bog iron ore forms in pools like coal but 
there is a difference. It seems that organic matter is 
important in this work. Decaying plants and animals 
seem to hasten the process which othtrwize would be 
slow. 

76. Are all the varieties of iron formed in the same 
way ? 

Practically the same. The varieties differ in the 
amount of oxygen contained with the iron. This dif¬ 
ference causes some iron ores to be reddish, like ochre, 
and others metallic. 

77. Are iron springs the same thing you have been 
describing ? 

Yes, they are. You will see them near the place 
where coal-beds come up to daylight. Indeed one way 
to ffnd some coal blossom is to be on the lookout for 
these iron springs or iron bogs. 

78. You told us of the effects of heat on coal, does it 
ever change the iron ores ? 

Wherever a bed of iron ore has been heated by hav¬ 
ing lava near it or where it has been squeezed ” badly 
in the disturbances of the rocks, the soft limonite iron 
ore w r as changed into the hard shiny “magnetite” or 
“ hematite.” 

79. In what geological formations does iron ore occur ? 

Most of the English iron ore comes from the coal 

measures. Alabama iron ore is also from near the coal 
seams. The Silurian contains much of the iron ore. 

80. Does an iron bed have fossils in it as in a coal 
seam ? 

Yes. but the fossils are always of fresh water plants 
and shells. 

81 How much iron is there in the ores ? 

Magnetite is nearly three-fourths pure iron ; hema¬ 
tite or specular ore has nearly as much ; bog ore has a 
little over one-half iron. 




34 


MINING PRIMERS. 


82. Where are these ores mined ? 

In almost every state of the Union. Some ores are 
purer than others, but the Lake Superior region, Corn¬ 
wall of Pennsylvania, and Virginia, are turning out 
large amounts of iron ore. Michigan stands first in 
mining nearly 6,000,000 long tons of an average value 
of $2.70 per ton. Alabama and Pennsjd vania come 
next with 1,500,000 each. 

83. Do all kinds of iron ore produce the same kind of 
iron ? 

No. The red hematite is the most desirable iron ore. 

84. How much iron ore have we in the United 
States ? 

We produced 14,518,500 long tons last year. The 
consumption is 15,733,465 (according to the census). 
Each long ton of ore is equal to about 1,200 pounds of 
pig iron. 

85. Have any figures been given as to how long the 
iron ore supply will last ? 

It is predicted that we have only sufficient iron ore, 
now discovered, to furnish the United States for 110 
years, assuming that the consumption doubles every 13 
years, which it would do if it continued at the same 
rate as during the last 10 years. 

86. How thick are the iron ore beds ? 

Like coal, they may be found up to 50 fc et thick, 
though the purest seams are only about 4 feet. Like 
coal, also, the seam is underlaid by clay. 

87. From what you say of iron and coal, the plants 
and animals must play a very important part in Nature ? 

They do, and though we are exhausting the coal beds 
and iron mines, they return to the earth again. When 
we burn up coal, it goes up into a gas, that i? called car¬ 
bonic acid gas, what miners call choke-damp. That gas 
feeds the plants now living and they take the carbon 
out of the gas, put it into the grass or wood which soon 
decays and goes through the same process. ' So it is 



GEOLOGY. 


35 


with iron, when it rusts it falls into the soil and is 
washed back into some pool and we have iron ore again. 

88. Does anything else depend upon the plants ? 

Yes, natural gas and petroleum. They are the pro¬ 
ducts of decay of wood and vegetation. Some claim 
that petroleum, or mineral oil, was made by the decay 
of organic matter, perhaps of animals. 

89. Why is that so thought ? 

Because bis caves have been found containing bitu¬ 
men, the solid remnant of petroleum and with fossils. 
In one place there has even been a cave solidly full of 
fishes that have been changed into oily tar. At least 
the geologists are all agreed that petroleum was made 
from organic matter that lived in salt water. 

90. What is the objection to the belief that the oil 
came from trees and plants? 

Because petroleum rarely occurs in strata that have 
been heated. 



CHAPTER IV. 


91. What is natural gas ? 

It is a gas accumulated in the subterranean cham¬ 
bers. It was discovered while drilling for oil wells. 
All oil wells may yield gas, but gas wells do not give 
petroleum. 

92. How was it produced ? 

Do you remember Q. 8 in which it was shown that 
the movements of the rocks in the earth heated and 
changed the character of the coals from peat or lignite 
to Bituminous and from the soft coals to the hard coals ? 
In this process, the most of the carbon remained in the 
coal as the table in Q. 2 showed, while the oxygen and 
some hydrogen forming water was carried off while 
the remainder of the hydrogen and some of the carbon, 
combined as a gas or in different gases escaped into 
the strata where it was collected in the pores or in 
cavities. 

93. Is the natural gas, then, a remnant of the coal 
changes ? 

Yes, it is, and is found in the vicinity of the coal re¬ 
gions. A few geologists believe that fishes furnished 
the oil. 

94. Does the gas cover a large territory ? 

It is found in a greater area than that of oil. And by 
the finding of new wells the district is extending. 
There are 500 gas-wells in the oil country and its vicin¬ 
ity and these produce 100,000,000 cubic feet per day. 

95. At what depth is gas found ? 


GEOLOGY. 


37 


The depth is 2200 feet or so, though of course it 
varies. 

96. Is there any connection between gas and oil? 

Yes, the late Mr. C. Asburner who was the authority, 

says they are the same in a geological sense. 

97. Where does the gas occur, geologically speaking ? 

It is found in the flat or nearly flat beds of three differ¬ 
ent sets of strata. The most productive wells are in the 

Devonian sands. 
(See Question 18.) 
It is found in the 
lower Silurian lime¬ 
stones. It is in the 
Bradford and Shef¬ 
field sandsand 1,500 
feet below the Pitts¬ 
burgh coal. In no 
case, however, does 
it occur where the 
rocks are broken up badly or where the strata are not 
porous. We find oil and gas in the Cretaceous in 
Colorado. 

98. Why is the oil in a given stratum ? 

Because the rock B is porous and has a floor A of 
clay, if now the rocks above are so badly cracked as 
the oil to flow in from above, the oil will accumulate 
in just the same way as the artesian well waters do, 
Fig. 14. When a hole is drilled to the porous stratum, 
the oil, gas, or artesian water, according to the region, 
will flow out. 

99. Does the natural gas occur in the same way ? 

The stratum is there overlaid by a loof or cover of 

impervious material like clay, and the rocks below are 
broken or porous enough to let the gas rise as high as it 
can. 

100. What is the difference between a spouting well 
and a dry well ? 







38 


MINING PR1MKR8. 


When boring for any of the three substances one 
may finally drill down into a stratum that contains 
them. If they are under pressure they may spout up 
to the surface, otherwise not. For example, the well W, 
Fig. 14, is drawing water from the stratum B; if the 
accumulation is deep and extends up above the level 
of W. as at C, for instance, then the well will spout. 
But if the surface is more like that at D and W is 
higher, the water will only rise to some point like F. 
Now the first example is one of a spouting well, the 
second, of one that is a pumping well, it requires power 
to raise the water. A dry well would be one that either 
did not reach B or else went through A and let the 
water out. 

101. Is that the same with petroleum and gas ? 

Somewhat, though it is not like water in that there is 

no perennial supply. The rain is continually feeding the 
stratum B with water, but there is nothing to keep up 
the supply of oil or gas. The accumulations of ages may 
be exhausted in a few months. The spouting oil wells 
are the lucky strikes into the reservoirs of nature that 
have been long collecting. 

102. How is it accumulated underground ? 

In Figs. 15 and 16 you will see what I want now to 

explain. Rocks are 
quite porous, and some 
have caves caused by 
the action of under¬ 
ground currents of 
water. Sandstone is 
very porous, and so is 
shale, therefore oil and 
gas can circulate freely 
in them. Besides this 
limestone has caves in it 
something like Fig. 15. 
Water is a strong solvent as you have already seen in the 



Fig. 15. 




















GEOLOGY. 


39 


description of iron ore formation. If it flows long, it 
eats away the cave like at M and as it trickles from the 
roof of the cave it forms icicles of lime called stalac¬ 
tites. The Mammoth Cave, of Kentucky, and Ouray 
Caverns are good examples. Some caverns may not 
have stalactites. In the rocks are such caverns which 
somehow accumulated the oil and gas like in Fig. 16. 
Oil is lighter than water and so will float on top of it. 
So also gas will gather above the oil as in the figure. 
Now one man may sink a well at B and get 
gas only; another hole drilled at A will get oil and 
later gas; the hole sunk in C will strike salt 
water. As these have accumulated from the de¬ 
composition of coal or 
organic matter with great 
heat, the gas is under 
heavy pressure, just like 
steam in a boiler. It 
forces itself out through 
B, or else A or C, driving 
out the other materials 
first. It may be a long 
time before the oil is all 
forced out at A but in 
time the gas will escape. 

This has been the his¬ 
tory of several neighbors 
in the oil country. 

103. Where should one bore for gas or oil ? 

If one can strike the rocks of the oil-bearing series, 
one should try to reach a spot on the top of the folds 
of the strata. Experience does not prove this to be 
always true, but it naturally tends to accumulate in the 
gently crumpled strata. 

104. Why does the explosion of a cartridge at the 
bottom of a dry hole bring oil or gas ? 

In the oil country, you expect to find oil in certain 


771 

TTT 

TTT 

rr-T 



rii 

TT 

TT 

rn 

1 1,1, 

1 


L, 1 ) 

1 j 1.1 

TT 

1=3 

J-UU 

TTT 

Tri 

1 

1 l 

1 y —_ 

"TSv-G 


1 1 1 



w 

J “fegA LT----W A T1 t R 
-tS - T- — 1 ! — *F — I— 

l -J 1 - . 1 


Fig. 16 





























40 


MINING PRIMERS. 


rocks. If, however, you fail to get a pumping or a 
spouting well you simply have not bored into one of 
the caves or reservoir.'. But you may be near one. So 
by putting 50 or 100 pounds of nitro glycerine in the 
bottom of a hole and dropping a drill rod on it you 
may, possibly, break into a neighboring reservoir and 
so get oil, but it is not certain. This method is never 
advisable in shelly ground unless the hole is lined 
with tubing, for the blast will cause a caving that will 
be forever troublesome and has often resulted in the 
abandonment of the hole. 

105. Are there any surface indications ? 

Yes, what is called oil show is one. On the surface 
of pools or springs a scum floats and gives good sign ; 
while again there are what may be called burning 
springs—rising gases which may be set fire to. 

106. Where does the petroleum come from? 

Russia and America are the chief oil-producing 
countries of the world. But other countries have large 
supplies. Geologically speaking it occurs with natural 
gas. 

107 How much oil is produced in America? 

Last year it was 1,160,000,000 gallons. And since 
1870 it has been steadily growing from 1000 wells giving 
201,471,000 gallons until there has now been produced 
altogether 18,400,000,000 gallons. Russia, during 1886 
alone turned out 260,000,000 gallons ; Scotland has slates 
that are mined and hoisted to the surface where the oil 
is sweated out of them. The Kimmeridge clay of Eng¬ 
land, is able to furnish a one-half barrel of oil from every 
cubic yard. 

108/Is the supply without limit? 

Geologists estimate an area of over 200,000 square 
miles as having more or less oil. The amount can not 
be estimated but is still very large, and the number of 
spouting wells, while uncertain, has not been decreas¬ 
ing. The Census reports show that the United States 




GEOLOGY. 


41 


produced $223,066,388 worth of petroleum during the 
past ten years and $76,563,674 worth of natural gas. Some 
of this came from Colorado and California but far the 
largest amount is produced in States bordering on the 
Ohio River. The natural gas supply will be much more 
quickly exhausted than the oil and that of Ohio and 
Indiana will not last as long as the Pennsylvania gas 
fields. The average pressure of the gas in the wells 
owned by the City of Toledo, Ohio, is now only about 
115 pounds to the square inch. In 1889, it was 250 
pounds, and in 1890 it fell to 175 pounds. Many of the 
gas wells originally had a pressure of 400 pounds. 

109. Why is the origin of oil associated with coal? 

Do you remember how in Q. 8 we showed the coal to 
be a marsh product? You are aware of the miasma 
and gas that comes from a marsh—we call it marsh 
gas. Now, coal, when burned in the stove, or a 
coke oven or in a gas works, or in the analysis 
gives off some gaseous material, coal gas; some volatile 
liquid, as naphtha; some liquid as coal oil; some tarand 
a little pit h. We find in nature a similar series—gas 
called natural gas, or fire-damp if it occurs in a mine; 
that which comes out at springs or from bore-holes 
some light oils as rock-naphtha; liquid petroleum ; tarry 
substances like bitumen ; and some solid material like 
asphalt. From these similarities we believe that petro¬ 
leum had an organic origin. 

110 Has natural gas the same composition as marsh 
gas? 

Natural gas is composed of: 


Marsh eras. 95 "50$ 

Hydrogen. 200 

Oxygen. 1’50 

Carbonic Acid. 100 


Marsh gas is a compound of 1 part of carbon with 4 
parts of Hydrogen. Fire-damp is nearly pure marsh 
gas. (See Q. 65, Ventilation.) You see the gases are 








42 


MINING PRIMERS. 


about the same in composition, but fire-damp stayed 
in the seams and pores of the coal while natural gas 
succeeded in escaping. In the Anthracite region the 
rocks were nearly all broken up, thus giving escape to 
most of the gas which remained in the Bituminous dis¬ 
tricts. 

111. Is natural gas as dangerous as fire-damp ? 

Exactly as bad. The blowers, as you call them, that 
let in fire-damp at the faces of the coal is practically 
natural gas. That is why there is so much complaint 
about the leaky main pipes that carry natural gas. At 
the points of leakage the gas works into the ground 
and affects the air of shallow mines near by. 





CHAPTER V. 


112. What is petroleum used for? 

In the crude state, it may be used for common lubri¬ 
cants as for car wheels, etc. But most of it is distilled 
and from it a large number of substances are made. 
These substances are chemical mixtures of carbon and 
hydrogen in different proportions. 

113. How is it done? 

If you notice what was said in answer to Q. 100 you 
have an idea of the process. The petroleum is put into 
a huge boiler and heated very carefully to a tempera¬ 
ture of, say, 120° F., and kept there. At that point a 
number of light volatile oils are boiled out. These are 
the series of naphthas which evaporate readily, 
are easily ignited and, when mixed with air, form ex¬ 
plosive compounds. Then at a higher temperature ben¬ 
zine comes off. After that kerosene, or coal oil, which 
boils at 340° F., is driven off. By heating still higher, 
the heavy lubricating oils are obtained. At still greater 
heat, tarry matters and various coloring compounds are 
boiled and a refuse remains with more or less offensive 
odors. Remember, that each different quality of oil is 
obtained by keeping the petroleum at a fixed tempera¬ 
ture. This separation is not very perfect. The lightest 
of the oils are the purest and those which come off later 
have always an admixture with other oils, for neither 
can the temperature be maintained perfectly regular, 
nor can the volatilization be perfectly theoretical. 
And that is the trouble with our burning oils. If 
all the naphtha is not carefully driven out before 


44 


MINING PRIMERS. 


the manufacture of the kerosene begins, the coal 
oil will have some of these light products mixed with 
it and when you leave your 5 gallon can of oil near the 
stove or in a hot place some of this remaining naphtha 
which should have been driven off in the refinery, es¬ 
capes and if you light a match near it—pop goes the 
weasel. That is why kerosene is always labeled for 
“fire test.” If you value your property or life, be sure 
to buy only high test kerosene. Often these oils are 
spoken of as having a certain flashing test. By that is 
meant the degree of Fahrenheit at which the oil will 
give off dangerous gas. An oil is not safe if it has a 
flashing test of less than 103° F. The more naphtha 
an oil has, the lower is its flashing point. 

114. How are the other products obtained? 

Paraffine is obtained by chilling a certain grade of oil. 

Astral oil is only one variety of coal oil having a flash¬ 
ing point of 125° F. Gasolene is a very, light oil ob¬ 
tained from a careful heating of the first naphthas that 
come off. Then all the various bands of oil are similarly 
produced according to the temperature of boiling. 

115. What amounts of the substances are obtained? 

A Pennsylvania oil will give : 


Gasolene. 

Refined naphtha . 

Benzine. 

Kerosene. 

Lubricating oil.... 

Paraffine. 

Gas coke and loss 


. 15 per cent. 
.lO 1 per cent. 

4- per cent. 
.55- per cent. 
.17 5 per cent. 

2- per cent. 
.10- per cent. 


116. Could these gases and oils also be made directly 
from coals ? 

Yes, to a certain extent. But that w r ould require 
greater care and would cost too much. The gas works 
treat coal this way and drive out natural gas, produce tar 
and other substances beside the coke. In the old 
countries the peat bogs are utilized in this way to make 










GEOLOGY. 


45 


tar, paraffine, solar oil, acetic acid, naphtha, and gas. 
Vaseline, kerosene, aniline and many other materials 
are also made from petroleum. 

117. What is the price of petroleum ? 

That varies with the market. In 1864 when 1000 
wells were flowing the price was about $9'84 per barrel 
of 40 gallons .Now, with 3800 wells gushing oil, it aver¬ 
ages about 80 cents according to the Census j eports. 

118. In what way are gas and oil used for fuel ? 

Just as coal is use 1. They have carbon, hydrogen 

and oxygen and if these be burned with air, heat is 
produced. 

119. Explain, please? 

One pound of carbon, pure anthracite, burned in the 
air gives out 14,540 units of heat. Whether that carbon 
is burned slow or fast it will give so much heat and 
will, under a boiler, evaporate 147 lbs of w r ater from 
the boiling point. Now if wood, or oil, or gas, of peat 
has one half a pound of carbon in it, then 735 pounds of 
water will be evaporated by it. Any substance contain¬ 
ing hydrogen will also be able to evaporate water, and 
produce heat, because one pound of hydrogen, no mat¬ 
ter how it is combined, in peat or in gas, will give out, 
when burned, 61,200 units of heat and evaporate 6T8 
pounds of water from 212° Fahrenheit. 

120. How about the oxygen in the oil or gas ? 

That is not a heat producer by combining with the air. 

In fact the carbon and the hydrogen burn only, be¬ 
cause they rob the oxygen from the air. That is 
what we do. Our lungs are furnaces. We inhale oxygen 
and that with the carbon from the body forms carbonic 
acid just as the stove burning wood or the locomotive 
burning coal. 

121. How would you find the amount of heat in 
coal then ? 

Find how much carbon is in a pound of coal and 
how much hydrogen also, and multiply these parts by 



46 


MINING PRIMERS. 


the amount of heat to be obtained from burning one 
pound. 

122. Suppose 100 pounds of petroleum; now, how 
would you do it ? 

One hundred pounds of petroleum have 86 pounds of 
carbon, 12 pounds of hydrogen and 2 of oxygen. One 
pound of carbon gives 14,540 units ; therefore 
86 pounds of carbon will give 1,250,440 units of heat. 
12 pounds of hydrogen will give 734,400 units of heat. 
So one hundred pounds of petroleum gives us 1,984,840 
units of heat. 

123. What is a unit of heat? 

The amount of heat necessary to raise one pound of 
water 1° Fahrenheit. 

124. How does petroleum compare with oil and coal ? 

One pound of 

Petroleum will evaporate.22 7 pounds of water. 

Coke will evaporate.1B 2 pounds of water. 

Anthracite will evaporate.14*2 pounds of water. 

Bituminous will evaporate.15 5 pounds of water. 

Peat dried will evaporate.10 0 pounds of water 

Wood, dry will evaporate.7 5 pounds of water. 

125. Does it make any difference where or how these 
are burned ? 

Theoretically, no matter where or how the wood, 
peat or coke is burned, the same amount of heat is pro¬ 
duced. Practically, however, there is a difference. 
Some burn up fast and some slow ; some give a long 
flame while others give none at all. These affect the 
burning qualities under a boiler. So the “calorific 
value” of a coal depends not only on the heat it is cap¬ 
able of producing but also the kind of grate it is 
burned in and whether it gets draught enough. 

126. How much heat should one get from a long ton 
of coal like the soft bituminous coal described in Ques¬ 
tion 2 ? 

That coal contains 88 per cent, of C.; 6 per cent, of H., 









GEOLOGY. 


47 


and 6 per cent, of 0. One long ton of coal contains, 
therefore, 1972 pounds of carbon, 134 pounds of hy¬ 
drogen and 134 pounds of oxygen. All of the oxygen 
in the coal exists as water and as it takes one-eighth as 
much hydrogen as oxygen to form the water, so we 
must deduct 167 pounds of hydrogen for the water, 
because one-eighth of 134 pounds is 1675 pounds. The 
117'25 pounds of hydrogen remaining give 7,175,700 
units of heat and the 1972 pounds of carbon produce 
28,672,880 units. So that one long ton of this coal will 
boil away more than 36,200 pounds of water from 
the boiling, point, provided all of the heat goes into 
the process 

127. Then does natural gas serve as a fuel on the 
same principle? 

The quantity of freed hydrogen and carbon, as in the 
example above, determines the “calorific value” of the 
gas. A natural gas contains 709 units of heat for every 
cubic foot. That is when 1000 cubic feet of gas are 
burned, they give out as much heat as 55'4 pounds of 
the coal mentioned above. As the gas is free from 
sulphur it does not give as much trouble in iron smelt¬ 
ing as would coal. Practically, the Westinghouse Brake 
Co. evaporated 10 38 pounds of water for one pound 
of the coal and the same amount with 178 cubic feet 
of the gas. Whence it follows that 1000 feet of the gas 
is equal to 81*8 pounds of the coal. So that gas 
burns to better advantage than the coal. It takes, in 
other words, 81'8 pounds of coal to do what 55*4 pounds 
should do compared with gas. 

128. What is asphalt ? 

Asphalt is a solid bituminous substance that is the 
residue of nature’s distillation of coal by volcanic heat, 
or by subterranean heat due to pressure and contrac¬ 
tion of the earth’s crust. It is of variable composition 
because it is not a simple substance any more than is 
coal. It is a mixture of several hydro carbons. 



48 


MINING PRIMERS. 


129. What is it used for? 

The most extensive use is for sidewalks and pave¬ 
ments, and it is an excellent soft water tight flooring 
for cellars. 

130. Where is it found ? 

It occurs widely diffused throughout the world, more 
especially in the tropical regions. In the Isle of 
Trinidad is a remarkable lake of it, 66 acres in area 
and of unknown depth. This lake is semi-fluid, and in 
places, quite liquid. At the edges exposure makes it 
hard. Varieties of asphalt are found in other places 
as a bed between two strata. Then there are a number 
of harder varieties called ozocerite, bitumen, etc., which 
occur to a greater or less extent as a vein or a bed. 
Similarly, naphtha is found in some localities flowing 
out of the earth as a olear, colorless liquid. Finally, 
the asphalt deposits which assume the greatest indus¬ 
trial importance are those in which a limestone is im¬ 
pregnated with asphalt. These bituminous stones carry 
from 8 to 20 per cent, and may be at once crushed and 
prepared for the purpose of road pavements, etc. The 
U. S. have produced, during 10 years, 127,500 short tons 
of asphalt and 47 short tons of purified ozocerite. 



CHAPTER VI. 


131. Where do the minerals of zinc, lead, silver, and 
gold occur? 

The total zinc product of the world is obtained from 
the flat beds and deposits intercalated with the sedi¬ 
mentary strata. A large proportion of the lead is also 
mined out of the stratified rocks, while many of the 
ores of the precious metals occur in the same way. 

132. Do they only occur in the stratified rocks ? 

They are often found in the metamorphic regions 

and in the massive rocks. 

133. What are the massive rocks ? 

They are a class of rocks which have no tendency to 
break into plates or slabs, as would limestone or slate 
but are usually coarse grained crystalline and quite, 
solid. 

134. What are they called ? 

There are two varieties; called plutonic and volcan¬ 
ic. The first term embraces the granite, syenite 
and gneiss made up wholly of a mass of crystals of dif¬ 
ferent substances. The second includes fine grained, 
partially crystallized, and somewhat glassy rocks which 
are called porphyry, lava, or trap. 

There is a large variety of these rocks bearing dif- 
terent names according to their composition, but the 
ferms given are generic. 

135. Where do the plutonic rocks occur? 

They are found in large masses forming the backbones 
of all large mountain ranges and the summit of peaks of 


50 


MINING PRIMERS. 


the lesser mountains and sometimes intruding small 
crevices of the stratified rocks. Occasionally they occur 


as exceptional layers between 
other sedimentary rocks. Ex¬ 
clusive of the exceptions, the 
granite, gneiss and syenite are 
found below the lowest known 
fossiliferous strata, wherever 
one penetrates the crust suffi¬ 
ciently to reach these depths. 
• Or they are found underneath 
the upturned strata as in 
Fig. 8. 



Granite 


Fig. 17. 


136. What are the granites 


composed of? 

Crystals of quartz, orthoclase-feldspar, and mica. 
The quartz is a very hard white crystal, the feldspar a 
very soft pink or whitish compound, while the mica 
occurs in black or yellow glittering flakes. The color 
of the feldspar determines the color of the granite. 

137. Where may the volcanic rocks be seen? 

They are found as extensive vertical sheets that 
stand boldly above the surface like massive walls 
called dykes (A, Fig. 18); they may be found as exten¬ 
sive overflows poured out on the surface (B, Fig. 18); or 
as immense sheets between the strata. These are found 
in all regions of great disturbances—where the earth’s 
crust had been subject to the violent lateral pressure 
following the cooling and burst giving vent to the 
molten mass of matter from the interior. 

138. What are the porphyries composed of? 

Mineralogically, the rocks are merely a combination 

of some one of the feldspars with hornblende, or augite. 
One group contains a predominenceof orthoclase-feldspar, 
while the other contains the plagioclase-feldspar. Of 
the former we have Trachyte and Rhyoiite and the 
glassy obsidian (sometimes mistaken for Anthracite 





GEOLOGY 


51 





















62 


MINING PRIM EES, 


coal, sometimes for blackglass). Basalt and Doleriteare 
the commom forms oi the latter group. 

139. Can the two classes be recognized by the naked 
eye? 

The granite rocks are usually colored and some¬ 
what banded, while their 
crystals are intimately 
crushed together and 
mixed. The porphyries are 
quite characteristic with 
the feldspar crystals prom¬ 
inently figuring in a crystal¬ 
line base. They are gray 
or blackish in color. Some 
PORPHY /? V of the more recent porphy¬ 

ries are tinted, but also 
Fig. 19. much finer grained. The 

augite crystals are quite 
dark, if not black. See Figs. 17, 19 and 20. 

B 


Fig. 20.—Graphic Granite: a, cross-section ; B, longi¬ 
tudinal-section 

140. Are these, the primary rocks of the earth ? 
Geologists are not agreed upon this matter. Un¬ 
doubtedly the granites are below all the fossiliferous 
strata and unquestionably the volcanic rocks are ejected 



A 







GEOLOGY. 


53 


from below and may come from the center of the earth. 
But as there has been nothing to indicate either the 
texture or the composition of the primary rocks, our 
present knowledge does not extend beyond the age of the 
granite (the Archaean age). They certainly represent 
the oldest formation known to us. 

There are, however, some anomalies in the study of 
the granite rocks that lead geologists to the belief that 
they are altered or re-fused stratified rocks. 

j First. They occur between other strata. 

Second. Their massive conditions pass insensibly'into 
metamorphic gneiss on the one hand and into volcanic 
rocks by slight gradation on the other. 

141. Are the volcanic rocks 
regarded as the primary rocks ? 

It can not be said of them any 
more than of the granites that 
they are the primary rocks. By 
the term we mean the original 
magma of which the earth is 
composed. According to the 
theory of a planet cooling from 
an incandescent fused condition Fig. 21. 



GNEISS. 


(as is the Sun)to the present, there 

certainly should be a substantial homogeneity in the 
molten mass. Whatever composition it may have, it 
should be the same throughout, and a sample of that 
mass erupted in Asia, should be the same as one taken 
from the lava of California or of Vesuvius. But this 
is not the case. We find that neither the granites nor 
the volcanic rocks are uniform in texture throughout 
the world. There is great diversity of composition. 

The same being true of granitic rocks, there is a belief 
that both of these groups of crystalline rocks are not 
from the original molten mass, but come from some 
upper layer or sub-crust; that these sub-layers may, 
like the limestones and sand stones, have been produced 





54 


MINING PRIMERS. 


by atmospheric actions explained in Q. 23; and that they 
are strata which have not been any where exposed at 
the surface. 

142 Do they occur stratified? 

Only one form of the granite, which we call gneiss, 
may be said to be stratified. It occasionally grades into 
a laminated condition that is called schist, which often 
can not be distinguished from sand clays. This variety 
of rock is fissile though not like slates. (See Fig. 21.) 

As has been stated, the volcanic rocks may appear to 
be stratified but that is rather due to an intrusion 
which occurred after the sedimentary rocks were formed. 

The varieties of volcanic or plutonic rocks do, however, 
have a peculiarly jointed structure as may be seen in 



F g 22. 

Figs. 22 and 23 which represent the columns of volcanic 
rock, or Fig. 21, showing the peculiar dyke <>f volcanic 
material occurring along Lake Superior. Fig. 25 illus¬ 
trates the natural tendency of granite to jointy struct¬ 
ure, (See Q 47) and in Fig. 26 we have a sample of 
the jointy tendency of limestone or sandstone. 

143. Are these due to the same causes? 





GEOLOGY. 


55 


Joints in the stratified rock 
are probably the result of its 
shrinkage while in the act of 
consolidating from its sedimen¬ 
tary condition, or in the granitic 
rocks while cooling after the high 
heat to which it has been sub¬ 
ject. The columnar structure is 
doubtless equally natural to the 
eruptive rocks which cont- acted Fig. 23. 

144. Then you regard the plutonic 
and volranic rocks as having been 
once molten and subsequently con¬ 
solidated ? 

I would not say that of the granitic 
rocks though the volcanic rocks 
were, without doubt, ejected in a 
molten state from vents opened, down 
to some s< atsof fires below the earth’s 
crust or within it. 

Those who do not regard the gran¬ 
ites as primary rocks of the earth’s 
crust, believe them to be plutonic 
or metamorphosed under the action 
of enormous heat and pressure. They 
claim that the granitic rocks are of sedimentary origin 
and during one period of the earth’s cooling the con¬ 
traction caused such pressure as to raise their tempera¬ 
ture nearly to a melting point when they were altered 
from the condition of sediment to a crystalline state. 
Undoubtedly there is some granite which has been 
thus metamorphosed but it has been subjected te 
heat of all ages since the early Cambrian. When tho 
crushing was great and the wrinkling excessive, gneiss 
was produced. (See G, Fig. 27,) With a still greater 
shrinkage and compression, the signs of strati- 


wmile cooling. 



Fig. 24. 








56 


MINING PRIMERS 



Fig. 26 
























































GEOLOGY. 


"7 


fication, if they ever existed, would be entirely de¬ 
stroyed, a fusion would take place producing granite. 
However it is, there is no unanimity of opinion among 
geologists as to the genesis of granite and allied varie- 



Fig. 27. 

ties. You have the various views and we must hurry 
on to consider the influence which these rocks and the 
earth’s violent changes have, or had, upon the occur¬ 
rence of ores. 








CHAPTER VII. 


145. How do ores occur? 

In deposits which are called veins or beds. The 
former name indicates the metalliferous masses in the 
earth that crop out at the surface for perhaps miles in 
extent and continue down into the earth at an angle 
nearly vertical. Beds are those deposits which lie 
more or less flat. 

146. How were the-e produced ? 

It was said that the earth’s crust has been broken 
and seamed in every direction. Some of these were 
closed up again at once, others were filled at the moment 
of formation with igneous matter and still others filled 
with mineral in a greater or less degree at once, or sub¬ 
sequent to the Assuring. All of these may be called 
veins, but the first are called faults (Q. 38), the second 
class dykes, and the third class veins or beds. There 
is little doubt that veins are formed by pressure at right 
angles to the directions of the fissures. This explains 
why they usually occur in parallel series. 

147. How were these filled ? 

Some of these crevices or fissures have been filled 
from below, the mineral coming up in a state of fusion, 
in solution or in gaseous state, either derived from the 
molten interior of the earth or, probably,from the metal¬ 
lic layers of the sub-crust. Such veins are necessarily of 
great depth and usually are found alongside of or near 
the walls of dykes of igneous matter. The copper ores 
of Lake Superior and elsewhere, and the silver veins of 
Nevada and Mexico are of this class. 


GEOLOGY. 


59 


Some veins have been formed by a filtration into 
their creviees of mineralized solutions which may have 
been hot and alkaline, or not. These solutions either 
deposited their metallic contents into previously-formed 
cavities, or they attacked such rocks as were soluble 
and in the cavities thus formed substituted, by “met- 
asomatic” interchange, mineral for rock. The cavities 
are found either entirely filled with a single mineral com¬ 
pound as are the zinc mines of S. W. Missouri or Wis¬ 
consin ; with an agglomeration of minerals as in New 
Mexico, Illinois, Nevada, or Colorado; or with a number 
of minerals in layers forming a ribboned structure in 
the fissure-veins,or forming an onion-layed structure in 
the cavities. Finally, many cavities are merely cut 
away and stalactited, or else partially filled with mud 
and clay, the last substance to be deposited from the 
muddy waters carrying the mineral. 

Other veins are also formed by an impregnation of 
the country rock by a mineralized solution from which 
was deposited some of the mineral. Some of the gold 
mines of Colorado are of this character as also are some 
lead-mines in Germany. 

Finally, there are some curious exceptional veins tep- 
resentedlby the Bull Domingo, in Utah, and the Bassick, 
in Colorado. When the crevices were being opened in 
the regions mentioned, large, long, deep rents were 
made of irregular shape: the walls did not break clean 
and smooth as is the case with the normal veins; but. 
fragments of the country rock fell into the crevices and 
filled them completely. Subsequently a mineralized 
solution or vapor percolated between the bowlders and 
the mineral thereof was deposited a- a cementing mate¬ 
rial to the mass. Some veins or deposits have doubtless 
been formed by hot springs. The mineral then occurs 
in “ chimneys.” 

148. You spoke of metasomatic interchange, what is 
that process? 





60 


MINING PRIMERS. 


It is a process in which a current of water dissolves 
the limestone, while at the same time, replacing it with 
mineral. It was undoubtedly the mode of forming the 
mineral deposits of Wisconsin, Leadville, and other re¬ 
gions. 

149. Where should we look for metalliferous veins ? 

Exclusive of the beds of iron, (Q.72) and clay,or those 
of zinc and lead which are the results of a deposition 
from water currents carrying these in suspension, the 
metalliferous veins occur in regions of great disturbance 
and metamorphism. The disturbance is the prelimi¬ 
nary action to the formation of fissures,and the necessary 
conditions for their subsequent filling with mineral, are 
similar to those under which metamorphic action takes 
place. Hence we may look for mineral veins in the 
v icinity of regions of igneous activity. The exceptions 
referred to may be found in or along any of the fossilif- 
erous strata from the Silurian up. Some iron ore has 
been found in the lower Cambrian. Generally speaking 
there is no reason for the belief that only certain geologi¬ 
cal formations can contain mineral deposits. This rule 
may apply locally, but is not of universal application. 
Any metamorphosed stratum may contain veins. The 
relative age of a vein may not be known. For example, 
H, of Fig. 18, was filled sometime after the Silurian age. 

The Cambrian quartzites of Colorado are very rich in 
mineral which happens to have been deposited along 
the contact with the limestone above it. These are the 
famous “contact veins” of Leadville and Aspen, Colora¬ 
do. The mineral also enters into cavities and crevices 
of the limestone. At 0, Fig. 18, will be noticed a con¬ 
tact layer of porphyry, not o' mineral, which, however, 
is shown at H. 

As will be explained later, the presence or proximity 
of a porphyry, in sheets or dykes, is a very favorable 
indication for mineral. Porphyry appears to be the 
home of the mineral and hence whenever a member of 




GEOLOGY. 


61 


this class of rocks is found, we have reason to expect 
mineral in it or along the line of juncture with the 
sedimentary rocks. Fig. 28 is a portion of a vein at 
Leadville, which may be termed a “contact.” 

150. Are contact veins profitable ? 

Though they are not popularly so regarded, yet there 
are many examples of rich cnntact veins. “ Blanket” 
veins, that is, those which lie flat among the sediment¬ 
ary beds and perhaps are not at any edge exposed to 
daylight, are as a rule not very extensive or rich. Fis¬ 
sure veins are sought everywhere, particularly those 
with good walls,though that is only a miner's prejudice. 

151. What do you mean by walls ? 

When a rent is made in the rocks and the fissure 
opened, the faces of the crevice become the walls to the 





Fig. 28 . 


vein when it has been filled. It is believed by miners that 
the two smooth walls constitute an essential feature for a 
strong, continuous, rich vein, but as you have seen, they 
are mere accidents and a perfection of walls in no wise 



62 


MINING PRIMERS. 


affects or effects, quality or quantity of the enclosed 
vein matter in the lode. 

152. Is there any difference in meaning between lode 
and vein ? 

No ; lode is a corruption from the verb to lead and an 
outcrop is the sign that leads the miner to the vein. 

153. What is the difference between a deposit and a 
vein ? 

The former is a general term defining any accumula¬ 
tion of mineral, whether the shape is regular or irregular. 
Isolated bodies of mineral are called deposits. When 
the ore is quite regular and continuous we call the mass, 
a vein or bed. 

154. Does the ore in a vein solidly fill the entire space 
of the fissures ? 

The fissure being accidentally filled it may have ores 
filling the entire fissure, but that is rare. Usually the 
ore has mixed with it other substances which do not 
pay, yet must be extracted to get the precious metals. 
Or, the mineral may have accumulated along a thin 
streak of a few inches width, while the remainder is 




Fig. 29. 

barren quartz rock. The ore may occur only as a mass 
of specs dotting the rock here and there. When we 




GEOLOGY. 


m 


read that a vein is 10 feet wide it means, therefore, not 
that the ore which will pay for extraction is 10 feet 
wide, but that the crevice, in which some ore is scatter¬ 
ed, is 10 feet wide. 

155. Does the crevice always maintain the same 
width ? 

No: it “ pinches and shoots,”as it is called. This is 
easily explained. Imagine Fig. 29, a to be the original 
crevice made during the disturbances already described. 
Perhaps afterwards, further movement occurred. In 
such case tho two parts of the country, A and B on 
either side of the crevice may have shifted to the posi¬ 
tion, 6, leaving the ere vice,which was subsequently tilled, 
to have large “ pockets” for ore-shoots and small places 
where it is said to have “ pinched” the vein. 



CHAPTER VIII. 


156. What are ore shoots? 

That is a name given to the richer portions of a vein, 
which are of considerable extent. The term ‘‘pockets” 
designates bunches of mineral. 

157. What was meant by ribboned-structure and 
onion-layered structure in Q. 147 ? 

Many of the veins in the plutonic rocks look like the 
illustrations in Figs. 30 to 32, where the layers on the 
two sides are symmetrical. These would suggest that at 


A 



Fig. 30. Fig. 31. 

one time the layeis 1, 1, were deposited by one solu¬ 
tion ; later, 2, 2; after which 3, 3, were formed, and so 
on. Or they may have all been deposited from the 
same solution according to their insolubility; the inner¬ 
most one being that which was more soluble than 1 , or 



GEOLOGY. 


6*5 


even 4. 

Beds of mineral, exhibit 
similar structure as in 
Figs. 33 and 34, which is 
similar to the ore occur¬ 
rences in Missouri and 
Wisconsin. The heart is 
dry bone, A; the next 
layer is hematite, B ; the 
next calamine, C, etc., 
etc. 

158. Are these common ? 

Not uncommon. But as a rule, the mineral occurs in 
specs, streaks, or bunches, and mingled with fluor spar, 
quartz, or calc spar as gangue,or waste rock, on either 
side of which along the walls is a layer of clay called 
selvage, or arouge. This latter facilitates the breaking 
of mineral from the walls, as without it, the ore is 
not easily broken away free from the rock. 

159. Do these metals occur in a pure state? 

Very rarely. Gold is found pure in the veins—per¬ 
haps 90 per cent, of the world’s production being from 
the “native” metal. Of this quantity the portion re- 



Fig. 32. 



Fig. 33. 


Fig. 34. 







66 


MINING PRIMER. 


covered from the veins directly is not one-fourth of 
that which is obtained from the detritus of the eroded 
veins. Nearly three fourths of the gold production 
comes from placer washings. It occurs in thin wires 
or leaves, between slate3 or in quartz, or else in infin¬ 
itesimal particles in the porphyry or quartz veins. The 
remaining 10 per cent, is obtained from one of the 
chemical compounds of gold with tellurium, etc. The 
gold is recovered mainly by contact with mercury 
(quicksilver) which absorbs it. Silver is found native, 
and mined, but only in a few places—Peru, Norway, and 
the Lake Superior region having supplied the larger 
portion of it. Exclusive of these, silver is obtained 
from various minerals. Some mines have very rich 
pockets or accumulations of a ruby colored mineral (of 
which the Granite Mountain mine is a famous illustra¬ 
tion) ; in others it is found as a blackish mineral in specs 
or lumps, called “sulphurets” (properly,argentite); while 
in others the silver is in gray flakes, combined with 
copper, and called “gray copper” (tetrahedrite). By far 
the larger portion of the silver production of the world, 
comes from mines, the ore of which contains the silver 
sparsely disseminated through galena (a lead mineral), 
pyrites, (iron—, or copper—), zinc blende (sometimes 
called black-jack), and spathic iron ore. The minerals 
may only occur in the gouge of the vein, while the 
vein-matter is barren of any value, or it may be collect¬ 
ed in the vein-matter. Either the silver mineral is 
concentrated out of the mixture (see Surface A ppliances) 
to be afterwards melted down into bullion with pure 
lead or copper, or else this preliminary is dispensed 
with and smelting resorted to at once. 

Copper occurs native in the Lake Superior region, 
and in Arizona, from which is derived 20 per cent, of 
the world’s production, and 50 per cent, of that of the 
U. S.; it is found in combination with carbonic acid, 
forming a beautiful blue mineral known as azurite; 




GEOLOGY. 


57 


and it also occurs as a massive green semi-precious 
mineral called malachite; while fully 55 per cent, of 
the copper is smelted out of the various sulphide com¬ 
binations called pyrites, (chalcopyrite), bornite, and 
chalcocite. A majority of the copper mines are in fis¬ 
sure veins. 

Lead is mined all over the world in the form known 
as galena (combination of sulphur and lead). 

Leadville Colorado, is, however, a mining district 
which produced 300,000 tons of metal from a white 
crystalline lead mineral, called carbonates (cerussite). 
This is an oxidized form of galena, resulting from ex¬ 
posure to air and water. These deposits are believed 
to be exhausted. The veins of Leadville are flat (in 
limestone and between it and quartzite). Those of 
Illinois,Missouri, Nevada, Wisconsin and many districts 
in the Old World are of similar occurrence. (See Fig¬ 
ure 35.) All fissure veins in the western part of the U. 
S. carry galena. 



Fig. 35. 

There are only five minerals of iron sufficiently 
abundant to become ores—Hematite, Limonite, Sider- 








68 


MINING PRIMER. 


ite, Magnetite, and Pyrites. These are found in many 
parts of the world, in the Silurian beds, and in the 
crystalline rocks. 

Zinc is obtained from three minerals—zinc blende, 
calamine and smithsonite—which are usually con¬ 
centrated after having been mined, and then heated 
in retorts to volatilize the zinc which is received in 
condensors. 

Reviewing these statements, it may be said that iron 
ore occurs as a distinct bed and the native and carbon¬ 
ate copper ores are generally free from admixture with 
other ores, but all of the other metals named are found 
in greater or less association. Thus galena and blende 
are almost inseparable and rarely found alone 

Pyrites with silver and gold minerals are usual ac¬ 
companiments to the galena in fissure veins or in de¬ 
posits. The geology of one is therefore allied to that of 
the others. So, also is the mechanical and chemical 
treatment f r their recovery and extraction. 



Fig. 36. 

160. How much of these minerals is requisite to con¬ 
stitute an ore ? 

That depends upon the proximity of the mine to 
market, the method of mining, and the quality—that is, 
the character of the valueless portion of the ore. A 
mine very near a railroad does not require as large or as 




GEOLOGY. 


69 


rich a deposit as one which is located on the top of one 
of the Rocky Mountain hills. On the average, how¬ 
ever, an ore yielding $10 worth of gold per ton may be 
regarded as pay. In the Black Hills and elsewhere, 
$3 in gold will repay the cost of mining and treating 
one ton of ore, but the conditions are very favorable. 
In Leadville an ore yielding $25 in silver and lead may 
be regarded as very rich ore. In isolated communities 



the ore should carry $40 to pay the cost of mining, 
transportation and treatment. In some localities of 
Europe an ore having 3 per cent, of lead and 8 ounces of 
silver ($7 to $10) has paid 10 per cent, dividends to the 













































70 


MINING PRIMER. 


operators. The famous Comstock bonanzas only averag¬ 
ed about $80 per ton, from which must be deducted the 
cost of mining and treatment, the interest on the 
capital and the high charges for transportation. A lead 
and zinc ore carrying 200 lbs. of each per ton pays very 
handsome profits in Missouri. 

Iron ores should contain not far from 50 per cent, 
of iron to be profitable. Their value ranges at about 
$3 per ton. But like all these others, often the quality 
of the gangue determines the marketable value 
of the ore. 

161. In what way? 

If the minerals were perfectly free from admixture 
with other substances, the metals sought for and 
obtained from their smelting would also be pure. Any 
foreign substance which is associated with the minerals 
will, in the melting, necessarily affect the quality of the 
product. Thus 1 lb. of phosphorus in a ton of iron ore 
would ruin the pig-iron obtained therefrom for any 
purpose except the commonest. Steel could not be 
made out of such iron. Likewise 3 or 4 lbs. of sulphur 
would render the iron containing it toe brittle. In 
like degree, small amounts of bismuth and antimony 
would injure the lead for sheets or pipes; while the 
presence of pyrites in blen le would injure the quality 
of the zinc distilled therefrom, besides destroying the 
retort in which it is fired. Copper is likewise affected 
by the presence in it of iron or arsenic. More 
than this, as we learned under “Analyses of Coal, Ores, 
etc.’’and under “Surface Appliances,” the value of silver 
and gold may occur in fine flaky mineral. As this can 
not readily be concentrated, it would, therefore, be 
lost. No matter how rich it may be, the larger portion 
of the value had better been absent than present and 
misleading. 

The silver may be with the zinc; in which case 
unless it were previously ascertained, the concentrator 



GEOLOGY. 


71 


would be losing the most valuable portion of the ore. 
For usually, the concentrating plant is “set” for saving 
the lead mainly, and the zinc only incidentally. (See 
Q. 76, “Surface Appliances”.) On the other hand the 
silver value may be associated with the barytes rather 
than the other minerals. In this case without special 
provision, concentration is worse than useless, and the 
ore has, practically, alow value. The same is true of 
gold. It is not uncommon for it to be of the hard 
quality .or rusted over with pyrites so that it will be re¬ 
jected by the quicksilver which is employed for gather¬ 
ing it. Even a thick bed of fine quality coal is almost 
valueless if there are many “brasses” or “nigger heads” 
in it. 

162. Does the mineral character of a vein remain 
constant with depth? 

Not always so. Some fissure veins have a galena ore 
at the surface ; and rich copper bornite below; 
in many the zinc blende disappears at a few 
hundred feet of depth; in others, the zinc does 
not occur nearer to the surface. In many mines, the 
free or oxidized ores near the surface, change to sul¬ 
phides below. In very many di-tricts the vein matter 
for some distance down from the surface consists of a 
‘ cap ” of dense iron quartz below which are found the 
precious metals and minerals. The surface quartz of 
other fissure veins is honeycombed and barren, when 
the mineral has been washed out of the matrix by the 
solvent agencies, which have flowed subsequent to the 
deposition of the mineral. So it is evident that both 
the character and the value of the mineral of fissure 
veins may change. There existed some time ago a be¬ 
lief that fissure veins were richer at great depth than at 
the surface. But the many deep explorations have dis¬ 
proved this fallacy, as a rule of universal application. 

163. Is there any prevailing direction on the surface 


72 


MINING PRIMERS. 


or with depth which is paticularly favorable to rich 
veins? 

That is only locally true. There is no direction of 
outcrop or dip of vein which may be said to be univers¬ 
ally that of rich veins. The crevices and fractures rent 
in every direction were accidental and casual, (Q. 38) 
and in any given locality were in a direction at right 
angles to the pressure. As the direction of pressure 
was not the same all over the globe, the fissures would 
not be parallel. In limited regions, however, the veins 
are usually in parallel series. This gives rise to what 
is termed a “belt,” by which is known a district of 
parallel veins carrying similar mineral. Thus a silver 
belt, a copper belt, and a tin belt exist in one district. 

164. How is that explained ? 

At one time, a certain series of crevices were opened 
in the earth and, at that time, or later, were filled with 



Fig. 38. 

tin and copper by some mineralizing agency. Subse¬ 
quently there came other disturbances which broke across 
the country another series of fissures which were min¬ 
eralized with lead and iron. When the contortions of 
nature again rent the rocks in a different set of veins, 
which became receptacles for lead, we had the first two* 





GEOLOGY 


73 


vein belts intersected by this latest, or youngest, belt, 
Fig. 38 illustrates the appearance of the surface cut 
up by such disturbances as I have described. Neither 
the number nor the order is constant, so that the figure 
is merely one example of many. Fig. 39 is another 
example, showing the vertical arrangement and inter¬ 
sections of two old veins D and C by two of more reeeni 
formation. 

165. Are these intersections common 9 


Yes, and give rise to much litigation. For example, 
if M, Fig. 40 is a vein owned and operated by a certain 



pot-tv and i- reached in the course of work by another 
partv owning the vein N. the question naturally 

arises: Which is the contin - 



nation of N ; or. To whom 
does O belong? Do the 
veins intersect as in Fig. 40. 
or do thev drag a« i n Fig 41 ? 
Ordinarily, it is a difficult 
matter, unless the veins are 
so entirely different in 






74 


.MINING PRIMERS. 


character as to leave no 100 m for doubt. If the con¬ 
tents are somewhat similar, then the decision is not 
very easily made 

166. What determines the answer? 

When the veins are similar in gangue and mineral, the 
gouge, iQ. 1.58) may be the only guide. The presence 
and character of the gouge along 0 compared with 

those of M and N will deter¬ 
mine the identity to M or 
IN. The problem became 
ver v c o m pi e x, h o w e v e r, 
when the intersected vein 
slips, as already explained in 
Q. 39, and results in some 
such intersection as showm in Fig. 42 where the miner 
along N would find no vein on the other side of M and 
would hence follow M, until he is discovered or dis¬ 
closes the continuation 0. 



0 


Fig. 41. 


167. How will N be able to find the continuation of 

his vein ? 

By a rule which, though 
not infallible is almost 
always correct. You will 
notice in Fig. 39 how the 
veins were not only 
broken, but misplaced; 
this is the usual result of 

intersectionsand faulting. 

When in driving a gallery a cross course is en¬ 
countered its strike and pitch must be noted. 
Then the miner should cut through it to the other 
side, for the continuation of the vein on which 
he is driving may not be displaced. If it is dislo¬ 
cated, follow this rule. 

1. When the cross course (be it a vein, a dyke or 
only a slip) dips a way from you, the continuation 



GEOLOGY. 


75 


of the vein is on the side opposite to the direction 
in which the vein pitches. 

2. When t ! e cross course dips toward you then 
the continuation is on your right or left accord- 
ingas to whether your vein dips to the right or left. 

168. Please give an example.' 

Suppose you were following a vein which dips 
downward tow T ard the left hand. You meet a fault¬ 
ing plane. Drift through it to the far wall. Now 7 
drive a prospecting gallery to the right along the 
far wall, if you found the fault dipping away from 
you. 

If your gallery encountered an intersecting vein 
that pitched tow 7 ard you (if the floor of ttie gal¬ 
lery meets the fault, first) then after reaching the 
far side of the vein you would drift along that 
to the left The explanation for this simple rule 

is too elaborate for re¬ 
cital here. Fig. 43 is a 
plan of the mine ac¬ 
cording with this last 
instance. The arrows 
indicate the direction 
of the dip. The grained 
portion is the excess in 
width of the vein 
over the gallery. 

169. How far would 
one have to go ? 

That can not be given 
as a general rule. The average distance of the displace¬ 
ment of several thousand mineral-veins is about 16 
feet. The amount of the throw varies with the intensity 
of the action and perhaps the time that has elapsed 
since the fracture. 

170. Why do you drift along the far w all ? 







76 


MINING PRIMERS. 


Because one is then in “country rock” and can teadi- 
ly distinguish the vein-matter w*>en the latter is met. 
This would not be so easy if the gallery were driven in 
the faulting vein. 

171. Is there any change in value or amount of min 
eral at the points of intersection ? 

That is still a debated point. I would say from my 
experience and reading that the places of inter¬ 
sections of two metalliferous veins are usually richer in 
quantity than are other points of either vein. Drags. 
Fig. 41, are not often richer than adjacent portions. 

172. Does the direction ortheamountof the dip appear 
to have had any influence upon the richness of the 
vein 9 

Only locally, as explained in Q. 163. Tn a certain 
locality onlv the veins which dip to the West carry any 
valuable mineral while the intersecting series having a 
Southward dip are of poor grade. Not 20 miles away 
are three districts in all of which the South dipping 
veins are the only ones mined, not one of those dip- 
pins' Northward being of any present value. There are 
no West dipping veins. In Fig. 39 all of the four veins 
are quite valuable. 0 being very 
rich, and A having had three 
extensive pockets of high grade 
ore. 

Finally a very singular case of 
rich vein, is crudely illustrated in 
Fig. 44. A large fissure had been 
formed at some period of the 
earth’s history, but instead of 
being a clean break which was 
subsequently filled as shown in 
b lgs. 30 to 34, the break was a, very irregular one and 
the filling followed immediately after the fracture with 
fragments and boulders of the country rock that had 
been shattered by the forces. Soon a mineral impreg- 



Fiu. 44. 



GEOLOGY 


77 


nation took placeand the angular masses were cemented 
together by rich mineral which filled the interstices 
between the boulders. There are only two such mines 
known to the writer. 






THE CORRESPONDENCE SCHOOL OF MINES. 

The curriculum of the school covers the whole art of Coal and 
Metal Mining and the sciences related thereto. 

THE COMPLETE MINING SCHOLARSHIP. 

This Scholarship embraces Instruction in the following subjects: 

Arithmetic, Ventilation, Geology, Search for Coal, 
Modes of Working Coal and Metal Mines, Surveying Coal 
and Metal Mines, Mine Machinery, Ambulance, Mining 
Legislation, Mine Accounts. 

Price: $ 35.00 payable in advance, $ 40.00 payable in installments. 

THE MINE MECHANICAL SCHOLARSHIP. 

This Scholarship embraces Instruction in the following subjects: 

Arithmetic, Mechanics, Machine Design, Strength of 
Materials, Boilers, Engines, Hoisting and Haulage Ap¬ 
pliances, Pumps, Applications of Compressed Air, Me¬ 
chanical Ventilators, Mining and Drilling Machines, 
Mine Surface Arrangements, Practical Geometry”, Me¬ 
chanical Drawing. 

Price: $ 25.00 payable in advance, $ 30.00 payable in installments. 

THE METAL PROSPECTORS’ SCHOLARSHIP. 

This Scholarship embraces Instruction in the following subjects: 

Blowpiping, Mineralogy, assaying, Economic Ge¬ 
ology, Prospecting. Price: $20.00, payable in advance. 

THE FULL SCHOLARSHIP. 

This Scholarship includes all the subjects taught by the School in 
the other Scholarships. 

Price: $ 50.00 payable in advance, $ 55.00 payable in installments. 
Students holding the Metal Prospectors’ Scholarship can take 
The Complete Mining Scholarship by paying $30 additional, 

Or, The Mine Mechanical .Scholarship by paying $20 additional, 
Or, The Full Scholarship by paying $35 additional. 

For Particulars and Circular of Information, apply to 

THE CORRESPONDENCE SCHOOL OF MINES, 

Scranton, Pa., U. S. A. 

THE CORRESPONDENCE SCHOOL OF MECHANICS. 

(Conducted on the same principles as The Correspondence School 
of Mines.) Supplies a complete education in Arithmetic, Geometry 
and Trigonometry, Elementary Mechanics, Hydraulics, Pneumatics 
and Heat, Mechanical Drawing, Applied Mechanics, .Strength of 
Materials, Machine Design, Boilers and Engines, Electricity. This 
School was instituted to meet the wants of Engine Drivers, Ma¬ 
chinists, Shop Foremen, Firemen, Pumpmen, and others connected 
with machinery. The practicability of the system of instruction is 
evidenced by its great popularity. The complete Mechanical 
'Scholarship embrace^all of the subjects given above. Price: $35 
payable in advance, $40 payable in installments. A separate course, 
embracing the subjects of Arithmetic, Geometry and Trigonometry, 
Elementary Mechanics, Hydraulics, Pneumatics and Heat, and 
Mechanical Drawing. Price; $ 25 , payable in advance. For par¬ 
ticulars and circular of information, applv to 

THE CORRESPONDENCE SCHOOL OF MECHANICS, 

Scranton, Pa., U. S. A. 












